1. Field of Use
This invention relates generally to power transmission torque converters having an impeller for driving a turbine and having radially disposed stator blades. In particular, it relates to stator blades having adjustably movable sections for controlling power output of the torque converter and to actuator means for moving the sections.
2. Description of the Prior Art
In transmission systems using torque converters, regulation or control of the power output at the output shaft of the converter can be accomplished in several ways. For example, in some systems, a modulatable clutch is located between the prime mover and the input shaft to the impeller. Mounted on the output member of the clutch is a speed sensitive governor valve externally controlled by means of a pressure control valve, as shown in U.S. Pat. No. 3,202,018 to C. R. Hilpert.
In some torque converters, power output can be adjusted or controlled by means of a so-called ring valve, which adjusts the flow of oil available to the impeller and turbine to thereby change the capacity of the converter. However, in such systems, as oil flow is reduced, turbine efficiency begins to fall off, and this is undesirable. Additionally, the ring valve when nearly closed, can cause destructive cavitation pulsations that have been known to break and loosen vanes.
In other torque converters, power output is regulated by using so-called "switch pitch" stator blades wherein each of the stator blades is swung or moved as an entire unit. However, in such an arrangement, performance begins to decline at both high speed ranges and low speed ranges because movement of the entire blade displaces the leading edge of the stator blade from its most desirable angle of attack or entrance angle relative to the oil circulating for the impeller and stator. Furthermore, the mechanical controls for prior art switch pitch stator blades are typically very thin and held in position by a small diameter pin, and the blades and pins are subject to gradual destruction in use resulting from oil flow therepast.